This invention relates to fuel dispensing nozzles, and more particularly concerns a device for limiting the rate of flow of fuel through an automatic shut-off fuel dispensing nozzle, such that it is prevented from exceeding a preselected threshold flow rate.
Liquid and fuel dispensing nozzles are commonly used to dispense gasoline or other fuels into fuel tanks of motorized vehicles. Conventional dispensing nozzles include a nozzle body defining an internal flow passage extending between the nozzle inlet and its outlet. The inlet of the nozzle is connected to a supply hose which feeds a liquid such as pressurized gasoline or other fuel to the nozzle. This pressurized fuel passes through the internal flow passage to an outlet which consists of, or is connected to, a spout which serves as the discharge end of the nozzle. The spout is inserted into the neck of a motorized vehicle's fuel tank during filling operations. The pressurized fuel flow through the internal fuel passage is conventionally controlled by a valve which is actuated by a manually operated valve lever selectively depressed by the nozzle user during dispensing operations. Moreover, automatic shut-off nozzles serve to automatically close the flow valve when the level of the liquid in the tank (or a neck leading thereto) being filled reached a preselected level. This is normally accomplished by actuation of a vacuum operated release mechanism mechanically coupled with the flow valve.
Fuel, under pressure created by a pump, is fed through the nozzle at flow rates established by the pump capacity and the extent to which the valve lever is actuated. It has been found that the rapid flow rates capable of being generated by conventional fuel pumps feeding the nozzle produce gasoline or other fuel fumes which escape into the atmosphere. Due to the wide spread use of dispensing nozzles and the volume of fumes escaping during dispensing operations, government regulations have been passed which are designed to limit the rate of flow of fuel through the dispensing nozzle. By limiting the rate of flow, the amount of fumes escaping can be reduced to a level which is less likely to cause significant damage to the earth's atmosphere.